1. Field of the Invention
The present invention relates to the field of Super Twisted Nematic (STN) Liquid Crystal Display (LCD) technology, and more particularly, to an STN LCD driver using a circuit with fewer capacitors for driving voltage stabilization and improving display quality by stabilizing levels of driving voltages, and a method therefor.
2. Description of the Related Art
In a six-level driving method of an STN LCD driver, six driving voltages are used for driving a liquid crystal display. In detail, five driving voltages and a ground voltage are used. If the driving voltages have unstable levels, display quality may be degraded. Thus, to stabilize the levels of the driving voltages, the STN LCD driver uses capacitors, each of which is connected to a respective terminal where a voltage level is generated.
FIG. 1 is a schematic block diagram of a conventional STN LCD driver operated according to a six-level driving method. Referring to FIG. 1, the conventional STN LCD driver includes a driving voltage generating circuit 11 for generating five driving voltages, i.e., first through fifth driving voltages V0-V4, as well as a common/segment driving circuit 13 for generating a common driving signal COM and a segment driving signal SEG.
The driving voltage generating circuit 11 includes a voltage converter 111, a voltage regulator 112, and a voltage divider 113. The common/segment driving circuit 13 includes a common driver 131 and a segment driver 132.
In the conventional STN LCD driver, capacitors C0-C4 are connected to terminals from which driving voltages V0-V4 are generated, to stabilize the levels of driving voltages V0-V4.
However, as the capacitors C0-C4 for driving voltage stabilization occupy an increasingly large area, the entire chip area of the STN LCD driver increases. In addition, the capacitors C0-C4 for driving voltage stabilization fail to sufficiently stabilize levels of driving voltages for liquid crystal displays, thus degrading the display quality.